Particle performance is of concern in processing semiconductor substrates such as silicon wafers due to reduction in yield caused by particles adhered to the surface of such substrates. Particles in the process chamber that fall on the substrate surface during or after substrate processing can reduce yield. Therefore, it is critical to control particle counts in the process chamber to the minimum to ensure good yield.
Particles in the process chamber can come from many sources. Process gases and substrate processing can generate particles. Films, either from process gases or from process byproducts, deposited on the components in the process chamber or on chamber wall(s) can also generate particles. Particles can also be introduced into the process chamber during chamber hardware maintenance by various mechanisms, such as cleaning solution residues remaining in the chamber when placing the component back into chamber. The O-ring on the chamber gate valve can also generate particles if the gate valve is clamped too tight or if the O-ring is of poor quality.
Traditionally, particle performance of a process chamber is monitored by measuring particle size and number (or count) on a substrate after the substrate is processed. The particle performance measurement can be done regularly to monitor the chamber performance or can be done after chamber hardware maintenance to qualify the process chamber. If a high particle count on the substrate is detected, the particle source(s) needs to be identified and the problem(s) needs to be solved before further substrate processing can be continued or before the chamber can be qualified.
Traditionally, particle source identification is done by running design of experiment (DOE) of various chamber processing and/or hardware parameters. Substrates processed with the DOE are measured for particle performance to determine which parameter(s) affects the particle size and counts. However, such a particle source identifying process is very labor and time intensive.
In view of the foregoing, there is a need for a method and apparatus that provides an improved chamber particle source identification mechanism to reduce the time and resources used to identify the particle source(s). The improved chamber particle source identification mechanism can improve overall chamber particle performance and throughput performance.